In von Holdt U.S. Pat. Nos. 3,909,180; 4,004,448; and 4,487,564, various systems are disclosed for retaining multiple piece molds and dies together while they are being lifted or otherwise manipulated. Molds and dies are often large and heavy. Accordingly, potentially severe accidents can take place, for example, while an injection mold is being lifted, when the user has forgotten to secure the mold pieces together in some manner. In that situation, one of the mold pieces which is not in contact with the lifting hook can slip loose and fall to the floor. The damage to the mold or die can result in thousands of dollars. Additionally, the consequences can be fatal if a person is struck by such a large piece of steel.
In accordance with this invention, an improved safety lock system is provided for molds, dies and equivalent devices (which are contemplated to be broadly included in the term "mold"). By this invention, a mold can exhibit a fail safe aspect, in which it cannot be lifted by a hook of predetermined proportions unless it is properly closed. Thus, in an industrial operation, the safety of the shop can be significantly improved simply by providing a lifting hook of predetermined proportions as the only available means of lifting the mold. In that circumstance, the mold cannot be lifted unless it is properly closed. Additionally, in preferred structures of this invention, once they are engaged with the hook, the mold cannot be opened until disengaged once again from the hook.
Accordingly, by this invention, workers in the shop cannot make a mistake in the lifting and other manipulation of a mold to cause accidental opening, and greater assurance of safety is provided.
Additionally, the improvement of this invention is structurally very simple and inexpensive to manufacture, for good economy as well as improved safety.